TEMPERATURE-DEPENDENT ELECTRONIC-STRUCTURE IN A LOCALIZED-MAGNETIC-MOMENT SYSTEM - GADOLINIUM

At normal emission, the bulklike band in gadolinium overlayers on W(110) shifts toward E(F) from 1.64 eV at 310 K to 1.43 eV at 230 K in photoemission. This is accompanied by an increase of the feature width from 0.8 eV at 320 K to 1.1 eV at 230 K. The surface-state binding energy remains unchanged, though the width increases significantly with increasing temperature. The different effects of temperature upon the photoemission results obtained for the bulklike and surface states are interpreted as magnetic-order-induced band movement and spin mixing, respectively, and are discussed in the light of a quasiparticle theory. The band dispersion along SIGMABAR is also temperature dependent. We postulate that the exchange splitting of the conduction band is not uniform at different positions in k space.